The game of golf is becoming increasingly popular in the United States and internationally. Presently, golf players, both professional and non-professional, are continuously striving to improve their golf game. As a result thereof, there is a large market for golf equipment which helps the player improve their golf game. For example, it is well known that the physical characteristics of the club shaft of a golf club can effect the travel of the golf ball. It is also well known that graphite club shafts typically have a higher stiffness to weight ratio, lower shaft vibration, and are more resilient to fatigue than steel club shafts. Accordingly, many golfers are switching from steel club shafts to graphite club shafts.
Recently, some manufacturers have begun matching the frequency of the graphite club shafts in a set of golf clubs so that all of the golf clubs in the set have a good and consistent feel. Additionally, matching the frequency of the club shafts can allow the golfer to have better distance control and dispersion pattern control during play.
One way of matching the frequency of club shafts involves initially manufacturing a number of club shafts in the same fashion. Stated another way, a club shaft for a No. 1 iron is initially manufactured the same as a club shaft for a No. 9 iron. Subsequently, selected amounts of each club shaft are removed from the shaft butt section or the shaft tip section, or weight is added to match the frequency of the club shafts in the set.
However, this process is not entirely satisfactory because each club shaft must be individually frequency tested to determine how much club shaft should be removed or how much weight should be added to the club shaft to match the frequency for the set. Further, using this process, it is very difficult to replicate or replace a damaged club shaft in a set without re-testing the other club shafts in the set.
Additionally, most graphite club shafts are lighter than comparable steel club shafts. Therefore, the graphite club shafts have a lower swing weight than a comparable steel club shaft. One way of increasing the swing weight of graphite club shafts is to add lead tape, or weights to the head, or add lead powder or slugs into the club shaft. However, the lead tape, slugs, or weights frequently become loose and alter the desired swing of the club shaft. Another way of increasing the swing weight is to increase the wall thickness of the graphite club shaft. However, the resulting thicker walled club shaft is often too stiff.
In light of the above, it is an object of the present invention to provide a method for manufacturing a set of club shafts that allows the player to have increased control over the dispersion pattern and more distance control during play. Yet another object of the present invention is to provide a method for manufacturing a set of club shafts which give the player better control over ball spin. Still another object of the present invention is to provide a set of club shafts which do not have to be individually flex tested and/or frequency tested in order to provide an individually matched set of club shafts. Another object of the present invention is to provide a method for controlling the frequency of the club shafts without adding weight to the head or club shaft, or cutting of the club shafts. Yet another object of the present invention is to provide a graphite club shaft having improved swing weight and performance characteristics.